Metal founding – Process – Shaping liquid metal against a forming surface
Reexamination Certificate
1998-10-07
2001-03-13
Pyon, Harold (Department: 1722)
Metal founding
Process
Shaping liquid metal against a forming surface
C164S442000, C164S454000, C164S413000
Reexamination Certificate
active
06199621
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an installation for producing slabs in a continuous casting plant. The continuous casting plant includes a strand guiding means arranged following the casting mold and divided into segments which each is composed of a two-part segment frame whose frame parts are braced together by means of hydraulic cylinders, wherein pairs of oppositely located rollers for supporting and for conveying the solidifying cast strand are mounted in the frame parts, and wherein at least one of these rollers, i.e., the drive roller, is pressed with a defined adjusting force against the cast strand for transmitting the conveying forces.
2. Description of the Related Art
DE 19 63 146 C1 discloses a plant for producing slabs in which the parts of the frame of the strand guiding means with their oppositely located rollers are combined to form segments, wherein the segment frames are composed of two yoke frames supporting the rollers and the yoke frames are adjustable through tension anchors and spacer pieces to the casting size.
In conventional strand guiding stands using the segment configuration of the type described in DE 19 63 146 C1, in curved installations in which the cast strand is guided from the vertical casting direction into the horizontal rolling direction, the upper frame and the lower frame of each segment are braced relative to each other by means of four hydraulic cylinders which connect the frames and are arranged at the corners outside of the travel path of the cast strand. The adjustment to different strand thicknesses is effected by means of spacer pieces against which the frame parts are pressed.
Because of this type of construction, a change of the distance between the rollers during the casting process is not possible.
In order to eliminate this deficiency, DE 43 06 853 C2 proposes to arrange a hydraulic plunger cylinder between the spacer pieces and the respective side frame part and to dimension the angular piston of this hydraulic plunger cylinder in such a way that in the pressureless state the hydraulic plunger cylinder fixes the segment parts to that distance between the rollers which corresponds to the desired strand thickness. This measure makes it possible to adjust the guide rollers in three defined positions.
Since in these known guiding strands the hydraulic cylinders press the segment frame parts against the spacer pieces and, thus, cannot act directly on the rollers which support and guide the cast strand, at least one of these rollers, i.e., the drive roller, is pressed by separate hydraulic adjusting cylinders (usually two adjusting cylinders for each drive roller) against the cast strand with the adjusting force required for the transmission for the strand conveying forces. This is usually effected in the middle of the segment, so that, depending on the introduced force, bending of the respective segment side frame may occur.
SUMMARY OF THE INVENTION
Therefore, it is the primary object of the present invention to further develop the construction of the strand guiding means of conventional continuous casting plants and especially to improve the existing drive concept.
In accordance with the present invention, a continuous casting plant for producing slabs includes a strand guiding means arranged following the casting mold and divided into segments, wherein each segment is composed of a two-part segment frame whose frame parts are braced together by means of hydraulic cylinders. Rollers for supporting and conveying the solidifying cast strand are mounted in pairs opposite each other, wherein at least one of these rollers, i.e., the drive roller, is pressed with a defined adjusting force against the cast strand for transmitting the strand conveying forces.
The method according to the present invention provides that bracing of the segment frame parts is effected in an infinitely variable manner by means of position-controlled and force-controlled segment adjusting cylinders which are also used for applying the adjusting force for the drive roller required for transmitting the strand conveying forces.
In accordance with the present invention, each segment of the strand guiding means has four position-controlled and force-controlled segment adjusting cylinders which connect and brace together the two segment frame parts at a distance from each other without the use of spacer pieces.
The infinitely variable adjustment of the segment positions by means of preferably four position-controlled and force-controlled segment adjusting cylinders, i.e., a conversion of the conventional segment clamping cylinders into segment adjusting cylinders, produces a defined introduction of the adjusting forces for conveying the cast strand in the strand guiding means for different process situations. This leads to an improvement in conveying the strand out of the system during operation and in cases of interruptions.
In addition, the present invention makes it possible by an appropriate position-controlled and force-controlled adjustment of the segment adjusting cylinders to transmit the required adjusting forces for the driven rollers to the pair of rollers at the entry side or exit side at the edge of the segment. Consequently, the drive roller can be switched from the previously used middle position in the segment to the entry side or the exit side of the segment. The segment adjusting cylinders then additionally perform the task of transmitting the adjusting forces for conveying the strand; this provides the advantage that bending of the segment side frames due to the previously used adjusting cylinders for the drive roller arranged in the middle no longer takes place because these additional adjusting cylinders are advantageously no longer required.
The measures according to the present invention provide an optimum force introduction for transmitting the strand conveying forces and the additional advantage is that by appropriate control of the position and force of the segment adjusting cylinders an anti-blocking control as well as an anti-slip control becomes possible for the drive roller. The principles of anti-blocking and anti-slip control are known to a person skilled in the art: it is necessary to measure the respective velocities of the driving part (drive roller) and the driven part (strand), i.e., the circumferential velocity of the drive roller and the linear velocity of the strand, and, in accordance with the measured values, the adjusting force is accordingly controlled to avoid slip or to release a blockage. Sensors for measuring velocities are well known in the art.
The installation according to the present invention for carrying out the above-described method is composed of a continuous casting plant with a strand guiding means divided into segments, wherein each segment has segment frame parts which are connected to each other and braced relative to each other at a distance without spacer pieces by means of four position-controlled and force-controlled segment adjusting cylinders.
In accordance with an advantageous further development of the invention, the drive roller is arranged at the segment edge in the area of the entry side or the exit side of the segment without using the previously provided separate adjusting cylinders.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
REFERENCES:
patent: 5348074 (1994-09-01), Streubel
patent: 5709261 (1998-01-01), Streubel
patent: 5915460 (1999-06-01), Courson et al.
patent: 1963146 (1971-06-01), None
patent: 4306853 (1996-03-01), None
Fischer Lothar
Weyer Axel
Kueffner Friedrich
Lin I.-H
Pyon Harold
SMS Schloemann--Siemag Aktiengesellschaft
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